*{
    margin: 0;
    padding: 0;
}
html,body{
    width:100%;
    height: 100%;
    overflow-x: hidden;
    font-family: "微软雅黑";
    font-size:50px;
    margin:0;
    overflow-y:auto;
    -webkit-overflow-scrolling: touch;
    background: #fff4c4;
    padding:0
}
.top_bg_img{
    width: 100%;
    display: block;
}
.nav{
    width: 100%;
    display: flex;
    justify-content: center;
    align-items: flex-start;
}
.nav img{
    display: block;
    width: 25%;
}
#course_1,#course_2,#course_3,#course_4{
    width: 100%;
    padding-bottom: 26px;
}
.month1{
    width: 100%;
}
#course_1 img,#course_2 img,#course_3 img,#course_4 img{
    width: 100%;
    display: block;
}
.close{
    display: none;
}
#course_2,#course_3,#course_4{
    display: none;
}
.month{
    display: none;
}
#course_1 .month:nth-of-type(1),#course_2 .month:nth-of-type(1),#course_3 .month:nth-of-type(1),#course_4 .month:nth-of-type(1) {
    display: block;
}
